One type of giant clam turns out to be two separate species, report researchers who discovered the new species on reefs in the Solomon Islands and at Ningaloo in Western Australia.

Jude Keyse, a postgraduate student at the University of Queensland School of Biological Sciences, says the find was surprising.

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“DNA sequences strongly suggest that a distinct and unnamed species of giant clam has been hiding literally in plain sight, looking almost the same as the relatively common Tridacna maxima,” says Keyse.

“Giant clams can grow up to 230 kilograms (507 pounds) and are some of the most recognizable animals on coral reefs, coming in a spectrum of vibrant colors including blues, greens, browns, and yellow hues.”

Co-author Shane Penny, a postgraduate student at Charles Darwin University, says, “To correctly describe the new species now becomes critical as the effects of getting it wrong can be profound for fisheries, ecology, and conservation.”

Divers and snorkelers prize the giant clams, which are also a source of meat and shells.

Overconsumption by humans has depleted giant clams populations in many areas and most giant clam species are on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species.

Keyse says the discovery of a new species had implications for management of giant clams.

“What we thought was one breeding group has turned out to be two, making each species even less abundant than previously thought,” she says.